From the Eiffel Tower in Paris to U.N. Headquarters in New York City, hundreds of notable landmarks worldwide will join thousands of cities and millions of people in going dark for Earth Hour

The annual event, which first began in 2007 in Sydney, Australia, is billed as the world's largest open-sourced environmental campaign, with more than 7,000 cities in 172 countries taking part. For one hour this Saturday, March 28, all non-essential lighting throughout the world will either be dimmed or turned off between 8:30 and 9:30 p.m. local time. This year's theme, "Change Climate Change," is particularly important ahead of a major climate change summit in Paris next December. 

“Climate change is a people problem," U.N. secretary general Ban Ki-moon said in a video supporting the event. "People cause climate change and people suffer from climate change. People can also solve climate change. This December in Paris, the United Nations is bringing nations together to agree a new, universal and meaningful climate agreement. It will be the culmination of a year of action on sustainable development."

Cologne Germany Earth Hour

Before and after lights out: Cologne, Germany goes dark during the 2014 Earth Hour. (Photo: Henning Kaiser/AFP/Getty Images)

While Earth Hour's message is serious, the event is also a lot of fun for participants, with cities around the world getting creative with the unusual darkness. Examples include Manila's glow-in-the-dark Zumba dance party, the world's largest candlelight dinner in Finland and a human-powered "energy floor" in front of the Eiffel Tower. Such broad appeal also presents an opportunity for communities to address local environmental issues, with the World Wildlife Fund and Earth Hour partnering on a wide variety of crowdfunding campaigns

“Earth Hour shows us what we can achieve together. From creating a forest in Uganda to lighting up entire villages with solar power in India and the Philippines, the power of the crowd to make change happen is phenomenal,” said Sudhanshu Sarronwala, chair of the board of directors for Earth Hour Global. “With Earth Hour, every light switch turned off is hope for climate action turned on.”

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Cities around the world to dim lights for Earth Hour
More than 7,000 cities in 172 countries are expected to take part in the one-hour event on Saturday.